Water waves in a shallow dish are 7.0 cm long. At one point, the water moves up and down at a rate of 4.0 oscillations per second. (a) What is the speed of the water waves?

0.28 m/s

Explanation:

From the equation of a moving wave,

V = λf Equation 1

Where V = speed of the water wave, λ = wave length of the water wave, f = frequency of the water wave.

Given: λ = 7.0 cm = 0.07 m, f = 4 Hz.

Substitute into equation 1

V = 0.07(4)

V = 0.28 m/s.

Hence the speed of the water wave = 0.28 m/s

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.